As recent rapid trend in modern electronic devices is not only toward lighter and smaller devices, but also toward multi-function and high-performance devices, the integrated-circuit (IC) fabrication and technology has to evolve correspondingly toward a more high-density and miniature design so as to allow more electronic components to be received inside limited chip space. Consequently, the relating IC package substrate and the package technology are evolved accordingly to meet the trend.
In the art, a package substrate can be formed by the core substrate process, which can be illustrated in FIG. 1A-1D. The upper-layer circuitry wires 12 and the lower-layer circuitry wires 13 are respectively formed on the top and bottom surfaces of the core substrate 11 as shown in FIG. 1A, before the circuit devices 14a and 14b are embedded in the core substrate 11. Opening windows are then formed in the core substrate 11 to be used to receive the circuit devices 14a and 14b, and the adhesive film 15 is adhered to the bottom of the lower-layer circuitry wires 13; thus, the circuit devices 14a and 14b can be disposed in the opening windows as shown in FIG. 1B. The dielectric layer 16 is then formed to cover the core substrate 11, the upper-layer circuitry wires 12, the lower-layer circuitry wires 13 and the circuit devices 14a and 14b. Then, the connection holes 17 are formed as shown in FIG. 1C. At last, the conductive metal layer 18 is formed on the dielectric layer 16 while enabling it to fill up the connection holes 17 as shown in FIG. 1D, so that the upper-layer circuitry wires 12, the lower-layer circuitry wires 13, and the circuit devices 14a and 14b can be connected to an external circuit. However, it is rather costly to form the opening windows in the core substrate 11. Also, it might need the costly and time-consuming laser engraving process to form the connection holes 17 in the dielectric layer 16 while enabling it to be aligned with the terminals of the circuit devices 14a and 14b. Therefore, it is in need of a new and advanced packaging solution.